1. Technical Field
The present invention relates in general to an improved composition of matter and, in particular, to an improved system, method, and apparatus for forming a novel composition of matter comprising an alloy of aluminum, lithium, magnesium, zirconium, and scandium.
2. Description of the Related Art
Metal objects are currently produced by thermomechanical processes, which include casting, rolling, stamping, forging, extrusion, machining, and joining operations. Multiple steps are required to produce a finished article. These conventional operations often require the use of heavy equipment and molds, tools, and dies. For example, a typical process sequence required to form a small cylindrical pressure vessel might include casting an ingot, heat treating and working the casting to homogenize it by forging or extrusion or both, then machining a hollow cylinder and, separately, end caps from the worked ingot and, finally, welding the end caps to the cylinder.
Conventional production methods are subtractive in nature in that material is cut away from a starting block of material to produce a more complex shape. Subtractive machining methods are deficient in many respects. Large portions of the starting material are reduced to waste in the form of cuttings. These methods produce waste materials, such as metal cuttings, oils, and solvents, which must be further processed for purposes of reuse or disposal. The articles produced are contaminated with cutting fluids and metal chips. They require cutting tools, which wear and must be periodically reconditioned and ultimately replaced. Fixtures for use in manufacturing must be designed, fabricated, and manipulated during production.
When a part is unusual in shape or has internal features, machining is more difficult. Choosing the machining operations to be used and the sequence of operations requires a high degree of experience. A number of different machines are needed to provide capability to perform the variety of operations, which are often required to produce a single article. Sophisticated machine tools require a significant capital investment and occupy a good deal of space. Use of the invention in place of subtractive machining provides solutions to these problems and disadvantages.
Another difficulty with conventional machining techniques is that many objects must be produced by machining a number of parts and then joining them together. Producing parts separately and joining them requires close tolerance machining of matching parts, provision of fastening means, such as threaded connections, and welding together of components. These operations involve a significant portion of the cost of producing an article, as they require time for design and production as well as apparatus for performing them.
Aluminum has been used extensively in aerospace and other manufacturing applications due to its high strength-to-weight ratio. To increase the usefulness of aluminum, various aluminum alloys have been produced, many being tailored to provide desired characteristics, such as increased fracture toughness. Common alloying elements include lithium, magnesium, copper, and scandium. However, the equilibrium solute levels (as measured in wt. %) in conventionally processed aluminum alloys are below that which maximizes the beneficial effect of the solute.
To increase the amount of solute levels in the alloys, rapid solidification processes (RSP) can be used. In these processes, a rapid quenching is used in freezing the alloy from a molten state, the solutes remaining in desired phases. After quenching, diffusion may allow for dispersion throughout the material and agglomeration at nucleation sites, further improving the characteristics of the alloy. While this type of process is widely used, the resulting product is typically in powder, flake, or ribbon forms, which are unsuitable for manufacturing applications requiring material in bulk form. Thus, an improved alloy and apparatus, system, and method of producing materials that avoids or eliminates many of the disadvantages of the prior art are needed and would be desirable.